It is well known to provide certain limited information regarding film contained in a cassette by means of a DX code imprinted on the exterior of the cassette. The code is typically embodied in conductive and non-conductive segments on the cylindrical body of the cassette which are sensed by electrical contacts in the camera. It is also known to provide DX information about the film in the form of an optical bar code imprinted on the cylindrical body of the cassette, the optical bar code having the advantage that more information about the film can be provided than is found in the conductive/non-conductive DX code segments. A problem with the bar code fixed on the cylindrical body of the cassette however, is that it requires the provision of a moving optical reader to be able to scan the length of the bar code which is costly and difficult to provide in a compact camera.
In U.S. Pat. No. 4,500,183, film related information is encoded on a rotatable magnetic disk axially mounted on the end of the film cassette and a drive mechanism is provided to rotate the disk so that the information can be read and recorded thereon by a stationary magnetic read/write head mounted in the camera. Although useful for its purpose, it requires costly disk drive and magnetic read/write components for its operation and reliability in reading of the magnetically recorded information can be adversely affected by variations in spacing between the read/record head and the magnetic surface as well as by the presence of stray fields emanating from drive motors in the camera.
In customary operation of a camera, when all image frames in a film strip are fully exposed, the film is rewound into the cassette to be removed and sent to a photofinisher for processing. At times, however, it is desirable to remove a cassette with the film unused or in a partially exposed condition. A common reason for this is to allow the camera user to change film types to better suit a particular photographic opportunity. In such a case, it is desirable to provide an indication to the user of the exposure status of the film as being unused, partially exposed or fully exposed so that double exposures are prevented if the cassette is subsequently reinserted into the camera.
In the above mentioned U.S. Pat. No. 4,500,183, provision is made for recording film use condition on the magnetic disk when film is rewound so that the camera can read the disk when a cartridge is inserted to give an indication to the user of the film use condition or to move the film to the first available unexposed frame. However, the disadvantage of this arrangement is that the cassette does not have a visual indication of the exposure status of the film and the cassette must be fully loaded and the camera operated in order to provide any indication of film use condition to the camera user. In preference to this arrangement, it is desirable to provide a visible indication on the cassette itself of the use condition of the film, particularly if the camera user has several cassettes to select from. This can be done by setting a rotatable indicator at one of several predetermined angular positions that visually indicates the condition of the film as being, for example, fully exposed, partially exposed or unexposed. For this purpose, however, some means must be provided to sense and keep track of the angular positioning of the indicator to assure proper positioning of the indicator at the conclusion of film rewind.
In the above mentioned cross referenced Pat. application Ser. No. 560,921, a film cassette and related camera apparatus is disclosed which utilizes measurement of a rotatable radial bar code on a disc at the end of the cassette as a basis for determining angular positioning of the disc and related positioning of film exposure indicators on the cassette. In the disclosed apparatus, however, only three indicator positions are given corresponding to unexposed, partially exposed and fully exposed conditions of the film in the cassette. It is desirable to provide a more precise indication of the partially exposed condition to give some measure of the amount of unexposed film remaining in the cassette. Moreover, no provision is made in the cassette for holding the exposure indicators in place after they have been positioned.
It is, therefore, an object of the invention to provide a film cassette with optically readable bar code information which can be used to set exposure status visual indicators on the cassette upon conclusion of film rewind into the cassette in such a way as to indicate the amount of unused film when in the partially exposed condition.
It is a further object of the invention to provide a film cassette having an optically readable rotatable bar code thereon for setting exposure status indicators with means for holding the indicators in position once the indicators have been set and the cassette removed from the camera.